Process for distilling liquids



Jan. 14, 1930. w. E. SANGER 1,743,488

PROCESS'FOR DISTILLlNG LIQUIDS original Filed July 23, 1923 Y Z520 Wa-ZZ'f/cazggei" deceased l l j Zin/021771052 Calfxec'uory Patented Jan. 14, 1930 UNITED STATES PATENT OFFICE WALTER E. SANGER, DECEASED, LATILI F CHICAGO, ILLINOIS, BY UNION TRUST COI- PANY, EXECUTOB, 0F DETROIT, MICHIGAN, ASSIGNOR T0 OSCAR H. 'WUBSTEIL 0F CHICAGO, ILLINOIS PROCESS FOB DISTILLING LIQUIDS Original application illcd .Tuly 23, 1928, Serial No. 653,074. Divided and this application iiled April 27, 1925. Serial No. 26,276.

This invention relates to aprocess for distilling various liquids,'and especially those which show a tendency to partially decomposedirectly or alone at normal pressure'. Such liquids are distilled in' a partial vacuum whereby the boiling point of the liquid is lowered in accordance with the degree of exhaustion. The improved process is particularly adapted for distilling crude glycerine, but the invention is not limited to this particular substance.

The object of the linvention is to provide an improved process for performing distillations of the nature referred to above.

The present invention may be considered in some respects as an improvement upon the invention disclosed in prior Patent No. 1,452,- 617, granted April 24, 1923.

This application is a division of applica" tion, Serial No.'653,074, filed July 23, 1923.

In the drawing, the ligure is a diagrammatic elevation, with parts in section, showing one form of apparatus comprised in the present invention. As shown in the drawing,the numeral 1 designates a still of the same general nature asshown in prior patent referred to above. The still is provided with an internal heating coil 11 through which steam or other heating medium may be circulated for evaporating the contents of the still. The still may be additionally heated by an external source in the usual manner if desired. A pipe 12 enters the top of the still and is provided with a perforated spider 13 at the bottom from which heated vapor is discharged into the glycerine or other liquid within the still to assist in the operation. A ring or coil 14 is positioned near the bottom of the still and is of slightly less diameter than the coil 1l. The ring is provided with perforations for directing fluid discharged therefrom toward the top -of the coil 11. Outside the still the coil 14 is provided with connections 15 and 16 by which either air or steam maybe introduced into the perforated ring 14. At the top of the still a second perforated ring 17 is provided having openings through which water may be discharged over the coil 11 and a connection 18 is provided for supplying water to the erforated ring 17. A pipe 19 leads upwardlly from the still 10 for conducting the va ors which pass through a trap 20 to a super eater condenser 21 in the manner described in the prior patent. A pipe 22 conducts the liquids which accumulate within the'trap back to the still.

The condenser 21 comprises a central chamber 23 and end chambers 24 and 25 separated from one another by heads 26. The chambers 24 and 25 are connected by a series of tubes 27 passing through the central chamber 23. Baflie plates 28 are preferably provided in the central chamber for directing the vapor from the pipe 19 about the tubes 27. The tubes 27 are supplied with vapors at a lower temperature than that of the vapor from the stilly in a manner to be explained so that the vapor'from the still will give up a portion of its heat to the vapor passing through the tubes and in this way a portion of the glycerine will be condensed and pass downwardly into a receiver 29. The uncondensed porition of the vapor from the distilling liquid will rise through pipe 30 and pass through pipes 31 and 32 to a second condenser 33. To eect this operation the valve 34 will be closed and the valve 35 open. The condenser 33 is of the same general construction as the superheater condenser 21 and is provided with pipes through which a cooling medium may be circulated, the medium being supplied by connections 36. Water may be used as a cooling medium or oil may be employed and the amount of condensation may be controlled by the temperature of the cooling medium which can be regulated as desired.

The condensate from the condenser 33 passes through pipe 39 into a collector 40. If further condensation is desired the vapors may pass from the collector 40 through pipe 41 to a third condenser 42 similar to the condenser 33. Valve 43 will be closed and valve 44 will be open to secure this operation. The cooling medium is supplied to the condenser 42 by connections 45. The lower portion of the condenser 42 is connected by a pipe 46 to a collector 47 and the upper portion of the collector 47 is connected by a pipe 48 to a suitable exhaust pump 49, by means of example,l if a suilicient y high temdperature condensing medium is used it wou1 be possible to obtain glycerine of dynamite grade without further concentration. By the use of successive condensers with decreasing temperature of condensing medium all of the lycerine may be condensed separately, giving varying concentrations of glycerol. In some cases a single condenser 33 in additlon to the su rheater condenser 21 will be suliicient, an in such cases the condenser 42 and its receiver 47 will be omitted.

The various receivers 29, 40 and 47 are arran d to drain into a pipe 50 which is connect by means of a pipe 51 to the bottom of a concentrator 52. The opposite end of the pi 50 is connected through pipe 53 to the ggttom of the evaporator 54, there being a siphon bend 55 in the pipe 53 for pur to be described. Valves 56, 57, 58 and 59 control the pipe connections so that the condensate from the different receivers may be conducted either to the concentrator 52 or the evaporator 54. The concentrator 52 is provided with a heating coil 60 which may be supplied with steam or other heating medium from any suitable source, and at the upper portion of the concentrator a separate coil or coils 61 is located to which a heating medium may be supplied by connections 62 for superheating the vapor arising from the concentrator. The glycerine in the concentrator will have a relatively high boiling point so that the exhaust steam from the pipe may be used for supplying heating medium to the coil 62 in the evaporator 54. The evaporator 54 will be supplied either with water through a connection 63 or with the distillate from the receiver 47, or perha s from the receiver 40. This distillate w ich enters the evaporator through pipe 53 will have the larger ortion of its glycerine previously condensed tlierefrom and returned to the concentrator 52 through the pipe 51 so that the liquid supplied to the evaporator will have only a small percentage of glycerine and is known as sweet water.

The vapor from the evaporator 54 may be passed through pipe 65 to the upper ortion of the concentrator 52'where it is su jected to the action of the superheating coil 61 and mingles with the vapor from the concentrator 52. It then passes upwardly throughpipes 66 and 67 to the superheater condenser 21 where under ordinary operation it is further superheated by the vapors from the still and then passes through pipe 12 to the discharge head 13 at the bottom of the still where it is discharged into the crude glycerine to aid in distillation the manner described in the prior patent.

It will be seenthat the exhaust pump 49 operates through the -various condensers in series to the top of the still 10. The upper portion of the evaporator 54 and concentrator 52 are connected with the bottom of the still so that the evaporator and concentrator will also operate at a reduced pressure due to the action of the ump, but in actual practice the pressure in t e evaporator and concentrator will be reater than that in the still, the difference 1n pressure usually corresponding to a head of approximately ten inches of mercur If the sti'll is operated say under 28 inches of vacuum, the vapors passing from the evaporator are at a temperature of steam at approximately 18 inches of vacuum, or about 173 Fahrenheit.

l The liquor in the concentrator is a highly concentrated solution of glycerine and water with some impurities and has a boiling oint of approximatel 300- Fahrenheit an the vapors passing om the concentrator have a temperature closely approximating this temperature. It has been found that these vapors from a concentrated solution of glycerine (70 to 90% glycerol) will carry over mechanically or through partial pressure an appreciable amount of glycerol, these vapors after concentration of the same analyzing an average of 3% of glycerine. Heretofore these condensed vapors have been collected as sweet water which yields an inferior product or were re-distilled with the sweet water if that method of disposing of glycerine in sweet water was resorted to. In the present improved process these vapors are not condensed directly but passed to the still in the form of vapors and are used for distilling the crude glycerine contained therein. With this arrangement more glycerine is obtained in a purer form, such as dynamite glycerine.

It is further found that by providing superheating coils (through which there is passed steam at a temperature'in excess of 360 Fahrenheit) in the upper part of the concentrator and passing both the vapors from the evaporator and the concentrator around these coils, that the resultant mixture of these vapors enters the superheater at a considerably higher temperature than if the vapors of the sweet Water evaporator are utilized and passed directly from this evaporator to the superheater condenser, as described in the prior patent referred to. W`ith the vapors from the concentrator entering the superheater at a considerably higher temperature the efficiency of the vapors introduced from the superheater into the still is increased and there is less steam required on the closed coil in the still and the crude glycerine is distilled more rapidly. As the vapors enter the superheater at a higher temperature there is a smaller difference in temperature between the vapors passing from the still and the injection vapors so that less glycerine is automatically condensed in the superlieater, and that which is condensed is of a higher degree of concentration.

By the use of successive condensers, as described with decreasing temperature of condensing medium, all of the glycerine may be condensed separately, giving various concentrations of glycerol in the different receivers. The piping of the return lines from the various receivers is so arranged that any part of the distillate may be returned to the concentrator or to the sweet water evaporator, as desired. As prevously pointed out, the sweet water evaporator 54 will be under a vacuum of approximately 18 inches, while the sweet water receivers are more thoroughly exhausted and are under a vacuum of about 28 inches. In order that the sweet water will run by gravity from the receivers to the evapoi'ator without danger of reverse How it is necessary that there be a considerable difference in level or head between the bottom of the receivers andthe level of the liquid in the evaporator. It is lfound that by using a siphon 55 in the receiver return line, as shown in the drawing, less space is required between the bottoms of the receivers and the top of the evaporator, since it is always necessary to lift a head of water to the top of the siphon before there is danger of return flow from the evaporator to the receiver. This reduces the height necessary for the equipment, allowing it to be installed in buildings with lower ceil- 4 ings. To further guard against any chance of return fiow of the sweet water from the evaporator through the receiver and through the exhaust pump where it would be lost, a check valve 68 may be placed in the line 53 to prevent reverse How therein. Since the same condition may exist -in the connection between the concentrator andthe receivers, a check valve 69 is also placed in the line 51.

In thev distillation of crude glycerine the coils in the still become coated with material known as foots which is baked on the coil,l thus interfering with the transfer of heat.

This foots is readily soluble in hot water and by providing a perforatedA pipe 17 over the top of the heating coil and of substantially the same diameter as the heating coil, hot water may be run over the heating coil from this open pipe and the coil may thus be cleaned and kept in a high degree of eiiiciency. The same result may be obtained by running cold water through the perforated coil 17 and keeping a small amount of steam turned on on the closed coil in the still. By placing a perforated coil 14 in the bottom of the still having connection for steam and air a violent splashing may be obtained and the .-ri'ill may be thoroughly cleaned.

Assuming that, for instance, dynamite glycerine is to be produced, the crude glycerine is fed from any suitable source, not shown into the still 10 to which external heat is preferably supplied. Air is now exhausted from the entire apparatus by means of the vacuum pump 49. The evaporator 54 contains water or is filled with sweet water from a previous distillation. This water is heated by the coil 62 and under the reduced pressure the sweet water vapor in the evaporator passes out through pipe into the concentrator 52 around the superheater coil 61 and into the superheatei' condenser 21. Here it passes through the tubes 27 and may be further superheated by the vapors of glycerine and steam which pass upwardly from the still through pipe 19 and pass around the condenser tubes 27. As the sweet water7 vapor which passes from the evaporator is saturated steam produced in a vacuum, its temperature is considerably below 212 Fahrenheit. The vapors passing from the liquid in the concentrator are produced under a vacuum, but due to the high concentration of glycerine therein they have a boiling temperature considerably in excess of saturated steam at the reduced pressure, and also partly due to the fact that these vapors carry some glycerol and glycol. The vapors from the evaporator are further heated by the vapors passing from the glycerine in the concentrator and the mixture of vapors from the evaporator and concentrator are both superheated bv the superheater coil 61. Accordingly there may be a difference in temperature between the vapors from the still and the vapors passing from the concentrator, and the mixed vapors from the concentrator being cooler than those from the still may act as a condensing medium and a part of the glycerine will be condensed in the superheater condenser 21. The amount of glycerine so condensed is controlled by the amount of superheating done in the concentrator.

If the vapors from the concentrator are superheated to a temperature in excess of the temperature of the vapors from the still none a ofthe vapors from the still will be condensed.

in the concentrator will be controlled by the amount of evaporating surface provided in the evaporator and concentrator and the teinperature which is there maintained. The

vapors which have been superheated in the concentrator 52 and in the condenser 21 pass downwardly into the still through pipe con` nection 12 and are distributed through the crude glycerine in the still by means of the perforations in the spider arms 13. The vapors thus introduced cause the hot glycerine inthe still to distill over through the pipe 19, as stated. It will be noted that the pipe connection 12 extends downwardly through the still from the top thereof in the arrangement shown so that the steam contained in pipe 12 may be. further superheated by the vapors of the distilling glycerine as they p'ass upwardly th-rough the still on their way through the pipe 19. The part of the glycerine condensed in thev condenser 21 drops into the receiver 29 from which it passes through pipe 51 into the .concentrator 60. Most of the water vapor which is carried along with glycerine vapor does not condense in the superheater condenser, but passes along with the remaining uncondensed glycerine through pipes 30 and 32 to the condenser 33. If the condenser 33 is the only additional condenser employed, then the remaining vapor is condensed and drops into receiver 40 and from there passes through the pipe connections shown either to the concentrator 52- or the evaporator 54. If the additional condenser 42 is employed, the portion of the vapor not condensed in 33 is condensed in 42 and passes through the receiver 47 to the pipe connection 50, and thence to the concentrator or the sweet water evaporator where the glycerine is finally concentrated to a finished product.

Perforated pipes 70 and 71 are provided for injecting open steam into the lower part of the concentrator 52 and evaporator 54, respectively. If by any cause an impurity such as trimethylene-glycol is run into the concentrator with the glycerine, this substance may be distilled from the concentrated solution of the glycerine containing this impurity by injectmg open steam through the perforated pipe 70 which is located below the level of the liquor in the concentrator. The open pipe 71 in the evaporator may be used in a similar manner.

In the distillation of chemically pure glycerine the process is the same as that described for distillation of dynamite glycerine, except y" that freshwater in place of sweet water?=,is

used for generating the vapor dischargedat the bottom of the still. In making 'ahigh grade of glycerine sweet water is unsuitable because some of the impurities of the sweet water are carried over into the still from where they are distilled over and collect partly in the concentrator making it impossible at times to secure a chemically pure rade to meet the requirements of the Unite States Pharmacopia. In carrying out the rocess with fresh water the water is supplie to the evaporator throughout the period of distillation by means of the pipe connection 63 and no sweet water is used for generating water vapors. The Water vapors from the fresh water pass around the superheating coil 61, but do not mix with vapors from the glycerine in the concentrator as the heating coils in the concentrator are not supplied with heating medium during the process of distillation and thus there are no glycerine vapors present. The sweet water which is condensed in the condenscrs 42 and 33 is held in the receivers 47 and 40 until completion of distillation when it is evaporatedin any suitable vessel. y

It will, of course, be obvious that the present process is not limited in its application to the distillation of glycerine. but that the same may be used in distilling other liquids which are distilled by steam or water vapors, and particularly such liquids which show a tendency to decompose when distilled at normal pressure.

It will be apparent that the superheater coil 61 could be located in the evaporator 54 instead of concentrator 52. In this case the pipe 65 would connect with the concentrator at the top thereof and enter the evaporator below the superheater coil and the pipe 66 would lead the superheated vapors from the top of the evaporator 54 instead of from the concentrator, as illustrated. The two devices 52 and 54 are very similar in construction and operation and in fact either could be called an evaporator or a concentrator. The terms have been applied in the manner used above merely for convenience and because the vessel 52 is commonly supplied with a more concentrated solution of glycerine.

It should be noted that the present invention is not limited strictly to the various details of the process and of the apparatus which have been particularly described, eX- ceptI as pointed out by the. accompanying claims. K

IVhat is claimed is:

1. The process if distilling glycerine comprisinzer the stps of vaporizing crude glycerine in a v sti l, vaporizing a concentrated glycerin@ mixture in a coneentrator, vaporizing water in an evaporator, maintaining a partial vacuum in said evaporator, concentra- .tor and still, mixing together and superheat- 111g the vapors from' the evaporator and concentrator, effecting transfer of heat to said superheated mixe( va ors from the vapor produced by heating t 1e crude glycerine in the still to further superheat said mixed vapors and to condense glycerine from the vapors from the still, further cooling the vapors from the still ,to condense more glycerine `therefrom ina second operation, conducting the glycerine condenscd from the vapors from the still into the concentrator, and introducing the superheated mixed vapors after the second heating thereof into the still.

2. The process of distilling glycerine comprising the steps of vaporizing a body of crude glycerne, condensing glycerine from the crude glycerine vapor thus produced by permitting transfer of heat from the vapor to a coolingr medium, the cooling medium being vapor produced by evaporation of substantially pure Water, the Water vapor being superheated in a partial vacuum before transfer of heatthereto from the Crude glycerine vapors, the superheated Water vapor being introduced into the body of crude glycerine subsequent to the transfer vof heat thereto from said crude glycerine vapor.

3. The process of distilling glycerine comprising the steps of vaporizing a body of crude glycerine, separately vaporizing a body of Water, condensing glycerine from the vapors of said crude glycerine, collecting the condensed glycerine, vaporizing the collected glycerine, mixing the vapors from said body of Water with the vapors from said collected glycerine, superheating the mixed vapors, said superheated mixed vapors being employed as the cooling medium for condensing the glycerine from the vapors from said body of crude glycerine, and subsequently introducing the mixed vapors into said body of crude glycerine.

Signed at Detroit, in the county of Wayne, and State of Michigan, this 31st day of March, 1925.

UNION TRUST COMPANY, By MORSE D. CAMPBELL, Trust Officer, Eeeutor of the Last Will and Testament of Waal/e1a E. Sanger, Deceased. 

